DEHP Impact On China Rana Liver Oxidative Stress

Phthalatic esters (PAEs) are an important raw material for many chemical products, widely used to produce plastic products. Di-2-ethylhexyl Phthalate (DEHP), one kind of PAEs, can be released from the plastics into the natural world, polluting the living environment of wild animals. The propagation and paedomorphosis of amphibians is conducted in the water and directly subject to the influence of chemical production to the aquatic environment. We have not seen reports about the oxidized damage of PAEs pollution to amphibians. Through the test and measurement of the change of activities of a series of antioxidase in the liver of Rana chensinensises after exposing them to aquatic environments containing DEHP, this paper discusses DEHP’s effect on causing oxidized damage to liver tissues and provides data to the oxidized damage mechanism of DEHP.In the experiment, Rana chensinensises are exposed to water bodies containing DEHP at respective concentration of10-7,10-6,10-5and10-4mol/L, and are taken of their livers as tissue homogenate after applying20d,30d and40d treatment respectively. Spectrophotometrical method is used to test the activity of SOD, GPX, CAT, GST and the content level change of MDA and GSH, and the paper discussed the oxidized damage effect of DEHP on hepatic cells considering histopathology:1. After exposed in DEHP water, the activity of SOD and GPX in the liver tissue of Rana chensinensises decreases and the decrease comes more significantly along with the increase of DEHP concentration and the exposure time. While to the contrary, CAT’s activity keeps increasing in the same process. The activity of SOD, GPX and CAT assumes obvious dose-dependent effect and time-accumulative effect. Enzyme GST’s activity changes dramatically, decreasing first and increasing later along with the extension of exposure time, taking on a "U" curve. MDA content increases with the extension of exposure time and have an effect of DEHP dose-dependence. GSH content assumes an overall decreasing trend.2. Observation using the histopathology method shows that after exposure to DEHP, Rana chensinensises have such pathological features as reduced cytoplasm in hepatic cells, cellular infiltration phenomenon of inflammatory cells, increased apoptotic cells and the appearance of adipose cell; such pathological features become more obvious along with the extension of exposure time. In the10-7mol/L DEHP group, after the exposure of20d, the pathological features are not so significant but they are significant after the exposure of30d and40d.Exposure to DEHP leads to significant change of the activities of relevant oxidation-responsive enzymes in the liver tissues of Rana chensinensises. DEHP may, through damaging the dynamic balance of free oxygen radicals inside the cells, cause over-oxidized damage of lipoid and further lead to cells damage. This toxicological effect is DEHP dose-dependent and time-accumulative.